All You Need To Know About Allergies : Causes, Symptoms & Types

Nowadays, the number of people with allergies has increased dramatically over the last 20-30 years in industrialized countries: it is now estimated that 25 to 30% of the population is affected by an allergy. Allergies are particularly common in children and young adults. However, everyone can suffer from it, with variations in percentage by country and age. We will see in this article what are allergies, their causes and their different types and symptoms. We will talk in an upcoming article about different cures and how to relieve allergies with natural remedies.

1. What is an Allergy?

Our immune system is specialized in the recognition of foreign bodies such as parasites, bacteria or viruses. When one of them penetrates into the body, the immune system produces specialized bodies charged with recognizing the intruder and then destroying it. Allergy is a dysregulation of the immune system which corresponds to a loss of tolerance towards substances supposed harmless: these substances are called allergens. The body of the allergic person treats these harmless substances as a threat and responds as well. Some body reactions include rash, itching in the eyes, runny nose, or even nausea or troubled breathing.

2. Why Do We Have Allergic Reactions?

Allergic reactions solely occur due to immune system’s attempt to save the body from the disease. However, an allergic reaction might not occur the first time you are in contact with the allergen or the allergy causing substance, but might occur on the consequent interactions of your body with the allergens. For example, the first time you inhale smoke might not trigger any allergies in you but the next time you inhale smoke, you might face an allergic reaction.
The mechanism of allergy takes place in two stages: a sensitization phase during which the immune system identifies the substance as an allergen. Then, when the organism comes into contact with the allergen again, the allergic reaction phase is triggered.
Allergic reactions are common and almost everyone faces them at one or the other time in their life. However, the intensity and the consequences differ from one person to another. The intensity of an allergic reaction can range anywhere from mild sneezing to life-threatening nose bleeding and thus, it is important that allergies should be taken seriously and considered while taking the smallest lifestyle related decisions.

3. What are the Most Common Causes of Allergies?

The most common causes include:

  • Environment
    Because of the modern industry, we live in a more polluted environment than before. Pollution is among the most dangerous factors that can affect the body and cause many allergies.
  • Home 
    Today, our homes are becoming smaller because of social and economic factors. Moreover, they are more distant from nature. Most of the materials that make up our furniture and decorative objects contain allergenic substances.
  • Food
    The composition of our diet has changed a lot. We eat fewer natural food products and more industrial and refined foods, containing flavor enhancers, colorants, preservatives, etc. that are not always suitable for our body.
  • Medication and everyday products 
    Medication and everyday consumer products, such as household products, soaps, cosmetics, or creams may also contain substances unsuitable for our body and skin. 
  • Heredity 
    The allergic ground of a parent increases the risk of allergies for his children.

4. Types and Forms of Allergies

4.1) Respiratory Allergy

Respiratory Allergy
A respiratory allergy is an inadequate or excessive reaction of the immune system when an allergen is inhaled by the individual: pollens for example. Respiratory allergy can be manifested as an allergic rhinitis or asthma.
Type Definition/Symptoms Causes
 Rhinitis Allergic Rhinitis is characterized by an inflammation of the mucous membranes (nose, eyes). It can occur episodically (Seasonal Rhinitis) or be present throughout the year (Persistent Rhinitis).
Symptoms are usually:

– Itching of the nose
– Breathing by mouth (only)
– A stuffy nose
– Itching of the throat / mouth / lips
– Red eyes, itching and swollen eyelids
– Loss of sense of smell
– Sneezing
– Runny nose
– Eyes crying

Seasonal Rhinitis:

– Pollen
– Dust mites
– Animal hair

Persistent Rhinitis:

– Mites, Cockroaches
– Smoke
– Dust
– Odors of chemicals

 Allergic Asthma Asthma is a chronic lung condition: Inflammation, increased mucus secretion, and muscle contraction cause airway narrowing that hinders air circulation in the lungs and makes breathing difficult.
The most common symptoms are:

– Acute shortness of breath and difficulty breathing
– An irritating dry cough, then greasy with significant secretion especially at night
– Sometimes a cough so violent that it causes vomiting
– Whistling in the chest
– Tightness and oppression of the chest
– Tingling in the throat

The causes of asthma are not yet well known. But genetic composition and the environment seem to play an important role.
But the most apparent causes are:

– Overexposure to house dust and mold
– The climate (air, pollution)
– Medication during the neonatal period
– Pets (hair, saliva, feathers, etc.)
– Pollen
– Mites

4.2) Contact Allergy (Skin Allergy)

Contact Allergy (Skin Allergy)
Contact allergy is a delayed reaction of the body to an allergen that may be in contact with the skin. Skin allergy can be manifested as Atopic Eczema, Urticaria or Contact Eczema
Type Definition/Symptoms Causes
Atopic Eczema Atopic Eczema is a fairly common skin condition that develops mainly in young children.

Symptoms begin with a simple red itch, then the skin dries and becomes rough in places, eventually the skin oozes and crusts form.

Known causes are:

– Animals
– Mites
– Some beauty products
– Genetic factors
– Baths or showers too prolonged
– Cold air in winter
– Stress
– Sometimes viral infections can aggravate atopic eczema

Urticaria Urticaria is an inflammatory disease of the skin. It is characterized by red or pinkis, superficial, rounded, blisters or plaques, with very limited contours, of varying size and number. These plaques are always associated with intense itching.

A plaque of urticaria is also fleeting, remaining only a few hours in the same place. Urticaria is often accompanied by edema at the extremities (face, hands, feet). These edema are normal skin colored, itchy and disappear more slowly in 24-48 hours, always without a trace.

The known causes of Urticaria are:

– Foods rich in histamine: eggs, nuts, alcool, chocolate, etc.
– Pressure: the lesions appear a few hours after heavy pressure (bike saddle, tight clothing, tool handling, long walk, etc.)
– Long sun exposure
– Cold: urticaria reaches parts of the body exposed to bad weather or cold water
– Viral or bacterial infections, parasites
– An abnormality of the thyroid
– It is sometimes induced by the ingestion of frozen foods or drinks
– Drugs (antibiotics, analgesics, anti-inflammatory, etc.)

Contact Eczema Contact eczema, more common in adults, is an allergic reaction of immunological hypersensitivity to contact with an irritant.
Contact eczema will be particularly marked at the exact spot where the allergen has come into contact with the skin, but it can then spread and even become generalized sometimes. The affected areas are very pruriginous (they strongly itch).
Contact eczema reveals:

– a variable red skin manifestation
– edema (congestion)
– small vesicles (mini-blisters) filled with a clear liquid; skin thickened and covered with patches (dander)
– crusts

The most frequent causes, but not limited, are:

– Pneumallergens (dust, mites, etc.)
– Rubber (elastic, tires, cable sheaths, gloves and boots)
– Chromium and chromium salts (dyes, cement, paint, bleach, stainless steel)
– Cobalt (magnets, tires, glues, soaps)
– The leather
– Formaldehyde (cosmetics (varnishes), deodorants, toothpaste, disinfectants)
– Nickel,
– Cleaning products

4.3) Food Allergy

Food Allergy
Food allergy is an abnormal defense of the body as a result of ingesting a food.
Type Definition/Symptoms Causes
 Food Allergy Often the symptoms are mild:

– Tingling on the lips
– Itching or rash
– Diarrhea
– Stomach ache
– Nausea and vomiting
– Weightloss
– But for some people, allergy can be very serious and even fatal. The food that caused the allergy must then be banned.

In USA, the following foods are responsible for about 90% of severe food allergies:

– Peanut
– Berries (almonds, Brazil nuts, cashew nuts, hazelnuts or avelines, macadamia nuts, pecans, pine nuts, pistachios, walnuts)
– Cow’s milk
– Eggs
– Fish
– Seafood (especially crab, lobster and shrimp)
– Soybeans
– Wheat (and cereal relatives)
– Sesame seeds

4.4) Allergy to Medication (Drug Allergy)

Allergy to Medication (Drug Allergy)
These are allergic-type reactions initiated by the immune system which considers certain drugs as foreign bodies, and it is one of the worst kinds of allergies that anyone can have.
Type Definition/Symptoms Causes
Drug Allergy Symptoms of drug allergy are very heterogeneous and can be one or more of the following symptoms:

– A skin reaction (urticaria, rash, rhinitis)
– Edema of the eyelids and eye irritation
– Generalized swelling of the face
– Digestive disorders such as vomiting
– Abdominal cramps or diarrhea
– Respiratory problems (cough, nasal congestion, sneezing, etc.)
– Occasionally, small pimples scattered all over the body that do not necessarily itch
– Sometimes an eczema

In theory, all drugs are likely to cause an allergic reaction. However, some are more so than others, either because the substance is very frequently consumed by the population, or because of the drug itself which is more allergenic, like antibiotics, nonsteroidal anti-inflammatory drugs (like aspirin) or general anesthetics used during surgery.

4.5) Allergy to Animals & Insects

Allergy to Animals & Insects
Allergy to animals is not produced by their hairs, whether short or long, but by their urine, saliva and the secretions of their sebaceous glands. By licking themselves, they deposit their allergens on their hair, causing allergic reactions in those who touch or approach them.
Type Definition/Symptoms Causes
 Allergy to pets and animals with hair Allergy to animals can be manifested in different ways:

– Respiratory problems like allergic rhinitis or allergic asthma
– Allergic conjunctivitis
– Skin issues: eczema or urticaria

Cats: Cat is the most “dangerous” in terms of awareness. The symptoms are mainly asthma and / or rhinitis
Dogs: Their saliva is less allergenic than that of cats.
Rodents: The urine of these animals, once dried, infests the ambient air of allergenic proteins that can be inhaled and cause allergic manifestations.
Horses: Sometimes the horse allergen is responsible for severe manifestations, such as the asthma attack

– Cats
– Horses
– Cattles
– Rodents (hamsters, rabbits, guinea)
 Allergy to birds Bird feathers are rarely allergenic, but they are home to many allergens, including mites. Bird droppings turn into dust when they dry out and cause allergic symptoms if inhaled.   – All types of birds
 Allergy to insects In some cases, allergy to insects and more particularly allergy to hymenoptera can be responsible for a serious reaction, like anaphylactic shock  – Fleas, ticks and cockroaches: it is mainly because of their sting that allergy appears
– Hymenoptera (bees, wasps, hornets, etc.): the allergen is contained in their venom.


5. What are Seasonal Allergies?

seasonal allergy

Seasonal allergies are the outcome to body coming in contact with certain harmless substances in the atmosphere in certain part of the year. For example, the complaints about seasonal allergies rise in the month of February in United States. This is due to the fact that in February, plants pollinate extensively because of favorable climatic conditions and as a result, the amount of pollen in the air increases. These pollen grains are the primary allergens in this case. However, like any other allergy, the intensity of the effects of allergy can vary a lot. Below are a few things that can affect the severity of a seasonal allergy:

  • Trees and grass that grow quickly during cold nights
  • Molds that grow in high humidity
  • High amount of pollen grains in the atmosphere during the morning
  • Soaring pollen count after rainfall
  • The speed of wind

Symptoms of a seasonal allergy

A seasonal allergy can easily be confused with a health issue. However, there are a few symptoms you should look out for:

  • Coughing is usually common in an allergic reaction
  • Some people also report weakness during this period
  • Sneezing, running and stuffy nose are also common symptoms of a seasonal allergy

6. What are Severe Allergies? 

Depending upon the conditions that a person is facing, an allergy is determined as a mild one of a severe allergic condition. In case a person has watery eyes, runny nose, sneezing and itching on the skin, it is usually a case of mild allergy. Whereas, if a person faces problems with breathing, high congestion in chest, excessive sneezing and hoarseness, it might be a case of severe allergy. Below are more symptoms that a person with severe allergies faces:

  • Coughing and wheezing
  • Low blood pressure
  • Chest pain
  • Dizziness
  • Pale skin
  • Hives on the skin
  • Excessive sweating
  • Swelling of throat, face or lips
  • Vomiting
  • Abdominal pain

In a severe allergy, the airways running from the mouth/nose to the lungs narrows and the throat swells which makes it nearly impossible to breath. The blood vessels expand and thus the blood pressure drops and in worst cases, to a life-threatening level.

7. What are Environmental Allergies?


These kinds of allergies happen when the allergens are present in the environment around you. Environment in this case does not mean the city or the country you live in but your immediate surroundings like your home and workplace. They are mild and go away as soon as you remove the allergen causing substance from the environment. However, they are highly irritating and can easily ruin a good day for you and people around you. There are medicines that can cure the environmental allergies but at the same time, you must follow a few strict rules for a healthy lifestyle at your home and work. Here are a few things you can do:

At your home:

  • Use a HEPA or a High Efficiency Particulate Air filter if you have a forced air furnace.
  • Keep the windows closed during the season of pollination to avoid having pollens inside your home.
  • Keep a check on the level of humidity in your home. Anything more than 50% will help in the growth of mold. Also, keep the corners and dark spaces of the house like basements and garage clean and fresh.
  • Never keep damp shoes and clothes in the storage. This might lead to mold growth.
  • Clear the washing machine as soon as the clothes are washed. Do not let them stay there for days.
  • Do not keep stuffed animals or toy on the bed or the sofa.
  • If at all possible, go for the hardwood flooring and ditch the carpets. Carpets are the breeding grounds for many allergens.
  • Always install an exhaust fan in the kitchen to remove the fumes quickly.


  • Avoid walking in the garden.
  • If you are highly allergic, avoid going to parks in the early morning. In case you need to exercise in the morning, stick to Yoga or probably hit the gym.
  • Wear clean socks and undergarments. Do not use scented deodorants and shampoos.
  • Carry your medication just in case you come across an allergen while out.

8. What is Gluten Allergy?


Gluten is a mixture of proteins combined with starch in the endosperm of most cereals. It constitutes about 80% of the proteins contained in wheat. It is this which is responsible for the viscous and elastic properties of flour. It absorbs water that is added to the flour and swells to generate a dough to be kneaded. During cooking, the gluten releases part of the retained water and binds to the starch contained in the flour, so as to ensure the cohesion of the bread. Gluten has long been recognized as a major allergen and antigen.

One must distinguish gluten allergy from gluten intolerance which are often confused together:
A gluten allergy is characterized by the total rejection of gluten by the body, resulting in well-known allergic reactions: urticaria, edema, asthma, itching, etc. but this form of allergy is relatively rare according to specialists.
In the other hand, in an intolerance to gluten, also called celiac disease, gluten triggers as an antigen an immune reaction that results in a chronic inflammatory reaction with ultimately tissue damage. Tissue damage progresses over time until complete destruction of intestinal villi, resulting in caloric and nutrient deficiencies such as vitamins or minerals.

At present, there is no medicinal treatment against celiac disease, the only treatment is to exclude any source of gluten from the diet for life.
More details about this subject will be shared soon in a dedicated article.

9. Common Issues Faced With Allergies

We have already discussed a number of factors and allergens that can cause allergies. However, there are a few common things linked to each of the allergy anyone can ever have. It is important that you know the answers to the following questions in order to avoid confusing your sensitivity towards allergens with a disease.

  • What are allergy reactions on face?
    All the allergies have one or the other effect on skin. While most of the allergies just develop rashes and a little amount of bloating which is easy to cure, there are a few cases where the skin can turn pale and yellow. However, just to be on the safer side, consult a doctor if your skin turns pale before calling it an allergic reaction. This hold true for the face as well. At most, if it is an allergic reaction, you should not have anything more than a rash or some acne on the face.
  • Can allergies cause fever?
    No. An allergy never causes fever. However, if you are in contact with an allergen for a prolonged period of time, you might get weak and feel feverish. In the event of feeling feverish, consult a doctor as you might have caught flu or viral.
  • Can allergies make you tired?
    Yes, they can. The body, especially the immune system consumes a lot of energy while fighting the ‘so called’ external agents. As a result, you end up feeling weak and tired.

10. How to Get Rid of Allergies?

Honestly, There is no special drug that can permanently make you immune to all the allergies. They cannot be simply cured. You carry them with you all the time. However, there are a few things that you can do to cure your allergies naturally. Here are a few tips you could use:

  • Consume apple cider vinegar to reduce the formation of mucous and avoid highly congestion and stuffiness in the nose.
  • Fill a Neti pot with a saline solution and pass it through your nostrils to remove all the allergens stuck in your system.
  • Consume probiotic food. This will increase the number of good bacteria in your system which indirectly reduce the sensitivity towards the allergens.

There are a lot more such remedies that you can use; and we will be sharing them soon in a dedicated topic.

11. When to Seek for Medical Care?

 You should consult your doctor if the following signs appear during an allergic reaction:
  • A whistle when you breathe
  • A fairly large chest congestion that makes your breathing difficult and wheezing 5 signs of asthma
  • An allergic reaction that over-the-counter drugs could not cure
  • An urticaria that appears as a result of exposure to an allergen (also called a rash). This condition may mark the onset of anaphylactic shock, an allergic reaction that could lead to death. Anaphylactic shock is most often associated with insect bites, but may occur in the presence of other allergens. So if you have a rash of hives, then see your doctor as soon as possible.

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